Hi

The external heat transfer coefficient is calculated using Gray and Webb (1986) correlations for a plate finned-tube heat exchanger and geometry parameters defined in Figure A.2 in attachment.

The correlation is valid for smooth fins and any number of tube rows:

hex = (j2_c/(Pr_air_c^(2.0/3.0)))*Cpair_c*Gc_air_c;

where for four or more tube rows (N ≥ 4),

j4 = 0.14*(Re_air_c^(-0.328))*((Sv_c/Sh_c)^(-0.502))*(Sd_c/do_c)^0.0312;

and for less than four rows,

jN/j4=0.991*((2.24*Re^−0.092)*((N/4)^−0.031))^0.607(4−N);

For N=1 if Sh=0.0 then hex would be zero too. Is it true?

Thank you.